Retaining wall members, such as planks, cross-bars and anchors, bulkheads and the like are well known in the prior art. These retaining wall members are often used to retain the embankments along a roadway or waterway.
Retaining wall members have also found use in the prior art to contain toxic wastes. For example, a toxic waste containment site may be surrounded by retaining wall members to prevent toxic materials from leaching out into the environment.
U.S. Pat. No. 4,863,315 to Wickberg discloses a polymeric retaining wall member having interlocking means along its edges. These interlocking means make the retaining wall member universally mateable with like members so as to form a locked wall.
With reference to FIG. 1, the retaining wall member described in the above-mentioned patent is generally designated by the reference numeral 10 and is seen to include a center section 1 and a pair of outer sections or side walls 3. Each outer section extends upwardly from the center section and forms an obtuse angle therewith.
Each outer section 3 terminates in an interlocking portion 5. The interlocking portion 5 includes a pair of flanged legs 7 and 9. The flanged leg 7 terminates in a T-shaped end 11 with the flanged leg 9 terminating in a L-shaped end 13. As described in the aforementioned patent, the interlocking means 5 permit the wall member 10 to be used in interlocking fashion with other wall members.
The Wickberg patent discloses that an extrusion process can be used to form the retaining wall members. This patent is totally silent as to what type of an extrusion process can be used. In addition, the Wickberg patent offers no guidance concerning what process parameters or variables may be critical in forming the retaining wall members. The inventor is unaware of any prior art technique that has been successfully used to form the Wickberg retaining wall members. Thus, a need has developed to be able to make the retaining wall member of FIG. 1, particularly in an economical and efficient form.
In response to this need, the present invention provides a method and apparatus for the manufacture of the retaining wall member of the type disclosed above. The present invention overcomes the prior art problem of being unable to manufacture the retaining wall member. The invention also makes the retaining wall member to precise dimensions and shape.